(CNN) -- Turkish voters go to the polls on Sunday in a crucial referendum on constitutional reform which could bring about the biggest change to the country's political landscape in three decades.

Prime Minister Recep Tayyip Erdogan has spearheaded the ruling Justice and Development Party's (AKP) campaign in favor of the reform package, arguing that the 26 amendments will bring greater freedom and democracy.

"Can there be anything wiser and more meaningful than going from a coup constitution to the constitution of the people?" Erdogan said in an interview with CNN, referring to the fact Turkey's current constitution was introduced in the wake of a military coup on September 12, 1980 -- 30 years to the day before Sunday's vote.

Erdogan was speaking aboard his campaign bus as he toured Istanbul on Friday in a last-minute pitch to voters. Thousands of enthusiastic supporters greeted him as he attended Friday prayers at a mosque on the outskirts of the city, chanting "Evet!" -- yes in Turkish and the slogan for those supporting constitutional change.

The proposed reforms include amendments to the country's judicial system, curbs on the power of military courts and an article abolishing the immunity currently enjoyed by the leaders of the 1980 coup. Other measures would guarantee gender equality and put in place measures to protect children, the elderly and the disabled.

Turkish lawmakers approved the package earlier this year but not by the two-thirds majority necessary for the government to press ahead without a referendum. The measures have also been ratified by Turkish President Abdullah Gul, Erdogan's AKP ally.

But Turkey's opposition argue that the reforms would further undermine the secular foundations on which modern Turkey was established in 1923.

They claim the reforms would give the prime minister too much power over the judiciary, making him a "modern-day sultan." Hasan Gerceker, the head of Turkey's Supreme Court of Appeals, this week warned that the changes would politicize the judiciary.

Berhan Simsek, head of the main opposition CHP's Istanbul branch, told CNN that by packaging the judicial changes with less controversial proposals, the AKP had "coated a poisonous pill with chocolate."

"This will put all the branches of government into one man's hand," Simsek said. "It will be one-man rule, like Saddam Hussein, or the Fuhrer."

Analysts say Sunday's vote is the latest confrontation in a power struggle between Erdogan's Islamist-rooted party and Turkey's secularist establishment, which have repeatedly clashed since AKP swept to power eight years ago.

The AKP narrowly avoided being banned from politics in 2008 when it was fined by the country's constitutional court -- the last bastion of secular opposition -- for alleged anti-secular activities. The court has also blocked legislation to lift a ban on Islamic headscarves at public universities.

"It started out as a referendum on constitutional reform package but it quickly developed into a confrontation between the government and the opposition. So it's really become a vote of confidence in the government," Istanbul-based journalist Andrew Finkel told CNN.

Turkey's main Kurdish political party, the BDP, has called on its supporters to boycott the vote altogether, saying their struggle for greater autonomy will continue whatever the result.

"Regardless of who wins, it won't stop the war," Mustafa Avci, the Istanbul co-chairman of the BDP, told CNN. "The referendum does not recognize the rights of Kurds."

Tensions boiled over in downtown Istanbul on Friday when Kurdish activists attacked buses and police vehicles with stones, wounding at least one bystander.

Erdogan insists be will do more to defuse the decades-old simmering conflict which has claimed thousands of lives -- but only after winning the referendum.

Opinion polls suggest Erdogan and his supporters may be facing their toughest political fight since winning office in 2002.

The AKP has triumphed emphatically in every major election since then and Sunday's referendum is also a crucial test of their enduring popularity ahead of next year's parliamentary elections, with almost 50 million Turks eligible to vote.

Kamer Katirci, a 19-year-old first-time voter, said he intended to cast his ballot "for my generation and for the generation to come after me to have a better life" as he collected brochures and asked questions about the referendum at a campaign stand in Istanbul's Taksim Square.

"People have their own opinions; some say yes, some say no," he said. "It may be a constitution that determines our path in terms of our future. One can't know if it would be for the better or worse, but the future will show us."

CNN's Ivan Watson and Yesim Comert in Istanbul, Turkey, contributed to this report.